The future of organ engineering and regeneration depends upon finding a method to successfully orient tissue layers formed from different cell types, typically epithelial/mesenchyme combinations. Modeling methods to make human skin have so far focused on constructing separate layers first and then layering one tissue type on the other to mimic the complete skin organ, and is the dominant method used today. In contrast, during embryogenesis and wound repair distinct tissue layers form simultaneously through a process relying on the cellular binding properties of cell populations. We have tapped into this innate ability of cell populations to recognize other cells of their type by creating a skin reconstitution method called a cell skin equivalent, or CeSSE ('cease'). Our skin model has been commercialized as "AccuskinTM" and we propose to characterize the skin formed and compare it to skin produced by another method, broadly known as the composite method. Immunohistology will be conducted to both illustrate the presence of common skin markers and to highlight differences in protein marker distribution observed in the two models and as compared to normal human skin. A key function of skin is to provide a barrier to the outside environment and a comparison of barrier properties will be assessed for the two different models by measuring cell viability in response to exposure to skin irritants by MTT assay. Cytokine production levels (IL1alpha and TNF-alpha) in the models will also be compared. In light of the favorable properties of Accuskin, its usefulness will be further shown by the ability to reconstruct diseased skin, exemplified by the mechano-bullosa disease recessive dystrophic epidermolysis bullosa, by using skin cells from cells derived from diseased patients. These proposed experiments will highlight broad functional differences in morphology, cell signaling between tissue layers, and stability/longevity between creating epithelial/mesenchyme tissue by cell sorting as compared to artificial layering of tissue used in composite models.